HO Scale Model Trains Database

Engines, Rolling Stock, Structures, and Accessories

According to the National Model Railroad Association (NMRA) standard S-1.2 predominantly used in North America, in HO scale, 3.5 mm (0.1378 in) represents 1 real foot (304.8 mm); this ratio works out to 1:87.0857142, usually rounded to 1:87.1. According to the MOROP standard NEM 010 predominantly used in Europe, the scale is exactly 1:87.[4] In HO, rails are spaced 16.5 mm (0.64961 in) apart which models the standard railroad gauge of 1,435 mm (4 ft 8 1Ã¢Ââ€ž2 in).